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5 

U.S.  Architect  of  Public  Biiildings 
Report 
1651/52 


THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

LOS  ANGELES 


aBONia  laiHdwvd 


if'' 


■^ 


REPORT 


OF    THE 


ARCHITECT  OF  PUBLIC  BUILDINGS, 


ACCOMPANYING 


THE  PRESIDENT'S  MESSAGE 


AT  THE 


SECOND  SESSION  OF  THE  THIRTY-SECOND,  CONGRESS. 


WASiriNCiTON: 
ROBERT  ARMSTRONG,  PRINTER. 


UBL 

REPORT  OF  THE  ARCHITECT  OF  PUBLIC  BUILDIXGS. 


Architect's  Office,  United  States  Capitol, 

Washington,  D.  C,  December  1,  1852. 

Sir  :  In  conformit}''  to  a  resolution  of  the  Senate  of  the  United 
States,  passed  August  26,  1852,  I  have  the  honor  to  lay  before  you  the 
i'oUowing  "nbstract  or  compendium"  of  my  annual  report,  which  is 
herewith  submitted  : 

Extension  of  the  Capitol. 

The  appropriation  for  continuing  the  w-ork  not  having  been  made 
until  the  3  4th  of  April  last,  the  buildings  are  not  as  far  advanced  as  I 
inticipated  at  the  date  of  my  last  annual  report.  The  contracts  all 
being  limited  to  existing  appropriations,  the  contractors  were  not  at 
liberty  to  make  preparations  for  supplying  materials  until  after  the 
passage  of  the  bill. 

As  soon  as  the  appro])riation  was  made,  the  contractors  promptly 
commenced  operations,  and  the  work  has  since  been  prosecuted  as 
rapidly  as  a  proper  regard  for  its  permanency,  durability,  and  beauty 
would  warrant. 

The  cellars  of  both  wings  are  completed,  the  arches  to  support  the 
basement  floors  ai'e  finished,  and  the  outside  marble  work  is  })rogrcss- 
ing  raj)idly. 

All  the  foundations  are  permanently  laid  on  the  natural,  undisturbed 
earth  ;  some  of  them  are  40  f^'t  deep,  and  none  less  than  15  feet 
below  the  ground  line  of  the  building.*  The  character  of  the  earth  un- 
der all  the  walls  is  the  sameythroughout,  being  a  stratum  of  compact 
gravel  of  several  feet  in  tliickness*  The  walls  are  all  built  widi  great 
care,  and  the  entire  sub-structure  is  massive  and  solid;*  The  stones  of 
which  these  foundations  are  constructed  were  tested,  at  the  recjuest  of 
a  speci;il  committee  ol"  th<!  House  of  Kepresentativcs,  by  the  late  Pro- 
fessor Walter  11.  Johnson,  whose  report  is  hereto  appended. 

The  rnarblc  for  the  exterior  has  been  delivered  as  rapidly  as  we 
have  re(|iiirfd  it ;  twenfy  e;irgoes  have  arrived  since  the  5tli  of  July 
last,  containing,  in  the  aggregMle,  ;J5,2'J(>  cubic  fix-t,  bciug  an  average 
of  1,487  cubic  li^et  per  week.  Jiefore  this  marble  was  adoj)led,  it  was 
tested  by  a  commission  ap[)ointed  for  the  purpose,  and  their  report  is 
hereto  annexed. 

in  coriformitv  to  the  proviso  contained  in  the  first  section  f>f  the  art 
of  Congress  approved  August  iJl,  1852,  I  appoint(ul  Mr.  John  C. 
Harkness  as  measurer  of  all  the  work  and  materials  of  the  ext(Mision 
of  the  Ca[)itf)l,  and  Mr.  Cornelius  .Jiieobs  receiver  of  materials  f()r  the 
north  wing,  and  Mr.  Willi;ini  J.  Smith  on  the  south  wing;  all  of  whoui 
were  duly  sworn  into  oiliee. 

All  the  work  done,  and  materials  fnrnished  by  contract,  have  since 
been  measured  by  Mr.  Harkness,  and  no  further  payments  were  madev 
until  the  measurement  was  reported  to  this  office,  in  conformity  to  tb«- 
aforesaid  act  of  Congress. 


4 

Tlio  whdlc  amount  nppropriatod,  thus  far,  for  the  exten- 
sion of  the  Cai)itol  is $000,000  00 

And  tlio  total  amount  cxpondt-d  to  this  date  (December  1, 

185:2)  is 495,799  97 

Leaving  an  unexpended  balance  of. 104,200  03 

There  \vill  be  recjuired  to  carry  on  the  work  during  the 
})resent  fiscal  vear,  ending  June  30,  1S53,  the  addi- 
tional sum  of. '. $400,000  00 

And  during  the  ensuing  fiscal  j'ear,  ending  June  30, 1S54,      600,000  00 

Making 1,000,000  00 

Library  of  Congress. 

On  the  27th  of  January  last  I  submitted  designs  for  reconstructing 
the  main  library  room,  with  arrangements  for  future  extension,  which 
were  adopted,  and  on  the  19th  of  March  an  appropriation  of  $72,500 
was  made  to  carry  out  the  plans.  Tlie  work  was  immediately  com- 
menced, and  every  possible  exertion  has  been  made  to  complete  it 
before  the  assembling  of  Congress  ;  it  will,  however,  be  ouf  of  our 
power  to  finish  it  entirely  for  several  weeks  to  come,  notwithstanding 
the  workmen  have  been  constantly  and  cn(Tgetically  employed,  night 
and  day.  The  entire  room  is  fitted  up  with  iron,  and  the  ceiling  is 
composed  of  the  same  material,  so  that  nothing  combustible  enters  in 
any  way  into  its  construction. 

The  damage  done  by  the  fire  to  the  western  front  has  all  been  re- 
paired. 

The  hot  water  furnaces,  for  warming  the  library  and  the  adjacent 
rooms  are  completed  and  in  operation. 

The  appropriation  made  for  "  the  repairs  .jf  the  Congres- 
sional Library,''  by  the  act  of  Congress  a})proved 
March  19,  1S52,  amounted  to $72,500  00 

Of  which  there  have  been  exj)cnded  to  the  present  date 

(December  1,  1S52) 51,703  24 

Leaving  an  unexpended  balance  of. 20,790  76 

The  Patent  Office  Buildings. 

The  interior  of  the  eastern  wing  is  nearly  completed  ;  the  basement 
and  principal  stories  are  now  ready  for  occupancy.  The  hot  water 
furnaces  are  completed  and  ready  to  be  put  in  oj)eration.  The  eastern 
portico  is  far  advanced  to  completion,  and  may  be  finished  in  a  few 
weeks. 

The  work  has  been  resumed  on  the  western  wing,  and  the  granite 
sub-basement  is  now  being  constructed. 

THOMAS  U.  WALTER, 

Architect  of  FuOlic  Buildings. 
Hon.  Alex.  H.  H.  Stuart, 

Secretary  of  the  Interior. 


Architect's  Office,  United  States  Capitol, 

Washington,  D.  C,  December  1,  1S52. 

Sir  :  I  have  the  honor  to  lay  before  you  the  following  report  of  the 
state  of  the  public  works  under  my  charge,  and  their  progress  during 
the  past  year ; 

Extension  of  the  Capitol. 

The  appropriation  for  continuing  the  work  on  the  Capitol  not  having 
been  made  until  the  14th  of  April  last,  the  buildings  are  not  in  the  state 
of  forwardness  I  anticipated  at  the  date  of  my  last  annual  report.  The 
contractors  for  furnishing  materials  were  not  at  liberty,  during  the  pen- 
dency of  the  bill,  to  make  any  arrangements  for  prosecuting  the  work, 
as  the  contracts  all  contain  an  express  stipulation  that  "  in  case  Congress 
should,  at  any  time,  ffiil  to  make  the  appropriations  necessary  to  carry 
on  the  work,  the  said  contracts  shall  be  suspended,  without  thereby 
creating  any  claim  on  the  United  States." 

No  preparations  were,  therefore,  made  for  quarrying  building- stone 
for  the  foundations,  granite  for  the  sub-basement,  or  marble  for  the  su- 
perstructure, until  after  the  passage  of  the  bill,  so  that  we  can  scarcely 
be  said  to  have  been  in  full  operation  until  the  middle  of  the  season. 

Immediately  after  Congress  had  made  the  appropriation,  the  contract- 
ors promptly  commenced  the  execution  of  their  several  contracts,  and 
the  most  energetic  means  were  used  throughout  the  remainder  of  the 
season  to  accelerate  the  work  as  rapidly  as  was  consistent  with  a 
proper  execution  of  its  several  parts,  and  a  due  regard  for  its  perma- 
nency, durability,  and  beauty. 

The  cellar  walls  of  both  wings  are  completed,  tlic  arches  to  support 
the  floors  of  the  basement  story  are  finished,  and  the  outside  marble 
work  is  progressing  rapidly  and  satisfactorily  ;  the  setting  of  the  marble 
has  been  commenced,  and  the  walls  are  raised,  in  some  places,  to  the 
height  of  twelve  feet  above  the  granite  sub-basement. 

Provision  is  made  throughout  the  entire  sub-structure  for  the  system 
of  warming  the  buildings,  described  in  my  last  annual  report,  and  all 
the  necessary  flues  are  commenced  in  accordance  tlicrewith. 

All  the  foundations  have  permanent  footings  on  the  natural,  undis- 
turbed earth;  ni;my  of  tlicm  are  laid  at  the  depth  of  ^/V;/  tl-ct,  and 
none  of  tln;rii  less  \.\v,n\  fifteen  feet  Ix-low  the  ground  line  of  the  buildings. 
This  inequality  of  depth  was  rendered  necessary  by  the  slope  of  the 
original  hill  on  which  the  Caj)ilol  is  built.  In  descending  from  the 
eastern  frf)nt,  where  the  foundations  are  drej)c(?t,  the  declivity  was 
made  in  steps,  so  as  to  preserve,  in  every  part,  a  horizontal  bearing. 
The  character  of  the  earth  under  all  the  walls  is  the  same  throughout 
the  work,  being  a  stratum  of  hard  and  com[)act  gravel  of  several  feet  in 
thickness. 

In  all  cases  the  footings  arc  at  least  two  feet  broader  than  the  walls 
they  support,  and  in  order  to  insure  the  [xrmanency  o(  tlie  western 
fronts  of  both  buiUlings,  where  the  foundations  were  of  such  extraordi- 
nary depths,  the  front  walls  and  the  portico  walls  were  united  at  the 
base,  thus  making  a  solid  foundation  o\' twenty  feet  in  width,  which  was 


6 

carried  up  ri^ht  foot  from  llio  footings  before  the  walls  were  set  off  to 
tlieir  roqnirccT  thii'kness. 

In  t]iiiL:;inG:  lor  llie  wostorn  foundations  of  tho  soulli  wing,  we  found, 
at  a  ilepth  of  thiyly  tcet  below  the  level  of  the  ground  on  the  eastern 
front,  architectural  fragments,  charred  timber,  and  other  debris,  from 
the  burning  of  the  Capitol  in  the  year  1814,  which  indicates  the  great 
amount  of  tiUing  up  that  lias  been  done  since  that  time.  After  passing 
through  tliese  masses  of  rubinsh,  the  natural  earth  was  reached  at  the 
deptli  o'i  thnty-cight  feet  below  the  ground  line,  and  at  two  feet  below 
this  undisturbed  surface  the  walls  were  founded,  as  before  stated. 

The  stones  of  which  these  foundations  have  been  constructed  were 
tested,  at  the  request  of  a  special  committee  of  the  House  of  Represen- 
taties,  bv  the  late  Professor  Walter  R.  Jc^hnson,  whose  report  is  hereto 
appended. 

The  contractors  for  furnishing  the  marble  commenced  operations  at 
their  quairies  in  Lee,  Massachusetts,  immediately  after  the  passage  of 
tlie  ap|)ropriation  l)ill,  and  their  first  cargo  arrived  on  the  5th  of  July 
last,  since  which  time  they  have  delivered  (ivcnty  cargoes,  containing  in 
the  aggregate  35,236  cubic  ieet,  making  an  average  of  1,4S7  cubic  feet 
per  week,  which  is  quite  as  fast  as  we  now  require  it. 

Before  this  marble  was  adopted  for  the  extension  of  the  Capitol,  it 
was  deemed  proper  to  test  the  several  specimens  offered  for  the  work, 
tor  the  purpose  of  obtaining  reliable  data  on  which  to  make  the  selec- 
tion. A  commission  was  accordingly  appointed  to  make  the  neces- 
sary' experiments,  and  on  their  report,  together  with  the  sanction  of  the 
Committees  on  Public  Buihlings  and  Grounds  of  b(jth  Houses  of  Con- 
gress, the  marl)le  we  are  now  using  was  adopted.  The  report  of  the 
commission  is  hereto  annexed. 

In  conformity  to  the  proviso  contained  in  the  first  section  of  the  act  of 
Congress  approved  August  31,  1852,  I  appointed  Mr.  John  C.  Hark- 
ness  as  measurer  of  all  the  work  and  materials  of  the  extension  of  the 
Capitol,  and  Mr.  Cornelius  Jacobs  as  receiver  ot"  materials  on  the 
north  wing  and  Mr.  WiUiam  J.  Smith  on  the  south  wing,  all  of  whom 
were  duly  sworn  into  office. 

Mr.  Harkness  has  since  measured  all  the  work  done  and  materials 
furnished  by  contract  from  the  commencement  of"  the  work,  and  re- 
jKDrted  the  same  to  this  ofhce,  in  conformity  to  tlie  aforesaid  act  of  Con- 
gress, and  no  further  payments  were  made  until  the  said  measurement 
was  received,  and  the  accounts  presented  in  accordance  therewith. 
By  an  act  of  Congress  approved  September  30,  1850,  there 

was  ap[)roj)riated   for  the  extension  of  the   Capitol  the 

sum  of 8100,000  00 

And  by  an  act  approved  April  14,  1852,  the  further  sum  of  500,000  00 

Making  ihe  whole  amount  appropriated  for  this  work  to  the 

present  date 600,000  00 

The  amount  expendf;d  at  the  date  of  my  last  annual  report, 

(December  23,  1851,)  was ' $88,082  86 


7 

Since  which  time  have  been  expended,  to  the  present  date, 

(December  1,  lS-52,) $407,717  11 


Making 495,799  97 

Which  leaves  an  unexpended  balance  of. 104,200  03 

600,000  00 

A  detailed  account  of  the  expenditures  up  to  the  31st  of  the  present 

month  inclusive,  will  be  transmitted  to  you  on  the  1st  of  January  en- 

sumg. 

There  will  be  required  to  carry  on  the  work  during  the 
present  fiscal  year,  ending  June  30,  1853,  the  additional 
sum  of. $400,000  00 

And  during  the  ensuing  fiscal  year,  ending  June  30,  1854    600,000  00 

Making 1,000,000  00 


Library  of  Congress. 

Immediately  after  the  destruction  of  this  portion  of  the  Capitol  by 
fire,  which  occurred  on  the  24t}i  of  December  last,  I  was  requested  by 
the  Commissioner  of  Pulilic  Buildings  to  make  an  examination  in  refer- 
ence to  the  extent  of  the  injury,  to  report  thereon,  and  to  prepare  plans 
and  estimates  for  repairing  the  damage. 

On  the  27lh  of  J;muary  I  submitted  a  design  flir  reconstructing  the 
principal  apartment  of  tlie  library  wiiliin  its  original  hmits,  witli  such 
an  arrangement  as  would  admit  of  its  luturc  enlargement,  together  with 
a  report  and  an  estimate,  all  of  which  were  subsequently  transmitted 
to  the  Senate  Committee  on  Public  Buildings  and  Grounds,  and  on  the 
19th  of  ^^arch  last,  an  act  was  passed  by  Congress  appropriating  the 
sum  of  872,500  for  carrying  out  the  design. 

As  the  plans  contemplnted  the  execution  of  the  entire  work  of  iron, 
proposals  were  invited  horn  several  establishments  which  were  sup- 
posed to  possess  undoubted  rir;iliti(\s  l()r  working  in  that  material  with 
expeditif)!)  and  aceuraev,  ;ind  the  cf)iitraet  w;is  finally  ;i\v;n'ded  to 
Messrs.  Junes,  lieebe  &  Co.,  of  N(nv  York,  they  being  the  lowest  bid- 
ders. Articles  of  agreement  were  entered  into  by  the  p.irties  on  the 
21st  of  June  last,  .uid  the  work  was  commenced  as  soon  as  the  j)atterns 
could  be  prepared. 

The  gre.'it  inconvenience  occasioned  by  the  lossof  tin?  il)rnier  liijr.'uy 
rendered  it  highly  important  to  have  the  room  fniished,  if  possible,  be- 
fore the  asseml)ling  of  Congress,  and  to  efii'ct  this  oiyect  every  possible 
exertion  has  been  used.  The  eontrncrtnrs  li;ive  kept  as  mnny  men  con- 
stantly emplovefl,  day  and  nifjht,  ris  the  nriture  of  the  work  would  ad- 
mit, and  have  left  no  means  unemployed  to  bring  it  to  a  speedy  con- 
clusion. Several  weeks  were  lost  by  unforeseen  difficulties,  which 
occurred  in  preparing  the  room  for  the  contractors;  and  considerable 
time  was  consumed  in  waiting  for  the  patterns  fi)r  the  f)inamental 
work,  which  the   pattern-makers  found  it  impossible  to  prepare  as  rap- 


8 

idlv  as  ihcy  wero  rr(iuire(l.  But  not\vitli.<tandino;  tliese  hindrarifces, 
wliii'h  could  neither  ha\'c  bceu  loresccu  nor  ax'oided,  the  work  has 
{)roL;ressed  with  uuexanipled  rapidity.  The  ceihn^,  which  is  wholly 
of  iron,  is  cnlircl}'  liuishcd,  and  thi^  alcoves  and  siielves  will  be  coni- 
j)letcd  in  a  few  days,  so  that  but  little  yet  remains  to  be  done  to  finish 
all  the  iron  work.  The  whole  t)f  this  immense  iron  room  will  there- 
fore have  been  cast,  fitted,  and  j)ut  up  in  less  than  six  months;  and  as 
lar  as  mv  own  knowledge  goes,  it  is  the  first  room  ever  made  exclu- 
sively of  iron. 

The  damage  done  by  the  fire  to  the  western  front  of  the  building 
has  all  been  repaired.  The  moulded  dressings  around  the  windows, 
and  all  the  injured  portions  of  the  w;dl,  the  columns,  and  the  pedestals 
have  been  removed  and  replaced  by  other  stone  from  the  same  quarry ; 
so  that  every  part  of  the  work  is  rendered  as  permanent  and  free  from 
blemish  as  it  was  before  the  fire.  Tiie  sculptured  panels  above  the 
windows  sustained  no  injur}',  except  being  defaced  by  smoke.  Such 
portions  of  the  inside  walls  as  w'ere  injured,  were  cut  out  and  replaced 
by  new  materials. 

Dcscr'qit'iun  of  the  dcsig7i. — The  librar}',  when  completed,  will  em- 
brace the  entire  western  projection  of  the  present  Capitol.  The  main 
room,  which  is  the  part  of  the  design  now  being  finished,  is  91  feet 
long,  34  I'eet  wide,  and  38  feet  high.  It  occupies  the  centre  of  the 
western  projection,  and  will  connect  at  each  end  with  a  room  of  cor- 
responding height,  29  feet  G  inciies  wide,  and  70  feet  2  inches  long. 
These  rooms  will  be  fitted  up  with  iron  cases,  and  iron  ceilings,  similar 
to  those  of  tlie  main  library.  They  will  also  be  roofed  with  copper 
laid  on  iron  ral'ters,  and  lighted  by  ornamenial  skylights.  The  con- 
nexion between  the  centre  and  the  end  rooms  will  be  made  by  open- 
ings of  10  feet  in  width  by  2S  feet  G  inches  in  height,  crowned  by  ellip- 
tical ardies.  These  ojicniiiL's  are  already  formed  in  the  walls,  so  as 
tf)  admit  of  being  cut  through  with  but  little  labor.  There  will  also  be 
two  additional  apartments,  each  IS  feet  G  inches  by  35  feet,  one  of 
which  is  now  temporarily  occupied  by  the  library;  thus  forming  a  suite 
o\  five  rooms,  embracing  an  extent  of  302  feet.  These  smaller  apart- 
ments will  be  approj)riated  to  the  use  of  Senators  and  members  of  the 
House  of  itepn.'scntalives  as  private  Heading  rooms. 

The  entire  f)lan  cannot,  however,  be  carried  out  until  accommoda- 
tions are  provided  in  the  new  wings  for  the  officers  of  Congress,  and 
the  committees  now  occupying  the  north  and  south  rooms  of  the  west- 
ern projection.  _l 

The  main  library  room,  which,  as  before  stated,  is  now  nearly  com-  I 

pleted,  embraces  the  space  occupied  by  the  old  library  before  the  fire.  I 

On  both  siflcs  of  the  rofjm  are  three  stories  of  iron  cases,  each  9  feet  6 
inches  in  height.  The  lower  story  consists  of  alcoves  projecting  8  feet 
6  inches  into  the  r(jom,  with  cases  on  each  side  of  the  projections.  The 
second  story  hfis  similar  fdcoves,  excepting  that  their  projection  is  but 
5  feet,  which  leaves  a  platform  of  3  feet  G  inches  in  width,  resting  on 
the  ca-ses  below,  and  which  constitute  a  commodious  gallery.  A  simi- 
lar platform  is  constructed  (jn  the  alcoves  of  the  second  story,  ff)rming 
a  gallery  to  approach  the  upper  cases ;  thus  making  three  stories,  reced- 


I 

I 


9% 

ing  as  they  ascend.     These  galleries  are  continued  across  the  ends  of 
the  room,  where  they  are  supported  by  massive  brackets. 

The  alcoves  are  nine  feet  eight  inches  in  width,  from  centre  to  centre, 
with  an  ornamented  pier  forming  the  head  of  each  projection.  The 
architraves  whicli  cross  the  alcoves  are  finished  with  shields,  crowning 
bands  and  corner  ornaments.  The  shields  are  designed  as  tablets  to 
receive  the  names  of  the  general  subjects  on  which  the  books  in  the 
respective  alcoves  treat. 

The  galleries  are  all  floored  with  cast  iron  plates,  and  protected  by 
pedestals  and  raihngs;  they  are  approached  by  two  semichcular  staii- 
ways  of  cast  iron,  recessed  in  the  end  walls  of  the  room. 

The  ceiling  is  wholly  composed  of  iron ;  it  is  suspended  from  strong 
iron  trusses,  which  likewise  constitute  the  support  of  the  roof;  it  rests 
on  twenty-four  mass}^  consoles,  ornamented  with  foliage,  fruits,  and 
scrolls.  Each  of  these  consoles  weighs  nearl}^  a  ton.  Their  projection 
from  the  face  of  the  walls  is  five  feet  six  inches,  their  height  five  feet 
four  inches,  and  their  width  twenty-one  inches.  The  entire  ceiling  is 
divided  into  deeply  sunken  panels,  and  embellished  with  ornate  moul- 
dings and  foliated  pendants. 

The  room  is  lighted,  in  addition  to  the  Jive  windows  in  the  western 
front,  by  eight  sky-hghts  in  the  ceiling,  each  six  feet  square  in  the  clear, 
filled  in  with  ornamented  glass,  and  protected  by  an  upper  sky-hght 
of  seventy-seven  feet  in  length  by  ten  feet  six  inches  in  width,  placed 
on  a  corresponding  angle  with  the  roof,  and  covered  with  thick  plates 
of  glass.  The  roof  is  covered  with  copper,  secured  by  copper  wire  to 
the  iion  rafters. 

Tiie  furnaces  for  warming  this  portion  of  the  building  are  completed, 
and  in  operation.  They  consist  of  hot  water  pipes  enclosed  in  cham- 
bers erected  in  the  old  furnace  room  in  the  cellar,  and  connected  with 
boilers  for  heating  the  water.  The  external  air  is  admitted  into  these 
chambers,  where  it  is  warmed  and  conveyed  b\-  flues  into  the  library, 
and  such  of  the  adjacent  rooms  as  were  heated  by  the  old  lurnaces. 

By  an  act  of  Congress,  approved  March  19,  1S52,  there 
was  a[)))ropriated  for  "the  repairs  of  the  Congressional 

Library"  the  sum  of. $72,500  00 

(Jf  whicli  there  have  been  expended,  to  the  present  dale, 

(Dec.l,  1802,) 51,703  24 

Leaving  an  unexpended  balance  of. 20,7 9G  76 

A  deta.il(;d  account  of  tlie  expenditures  up  to  tlie  31st  of  the  present 
month,  inclusive,  will  be  transmitted  to  you  on  the  1st  of  January  en- 
suing. 

The  Patent  Office  Buildings. 

The  interior  of  the  cnstern  wing  of  the  Patent  Office  is  nearly  com- 
pleted, the  basement  and  the  principal  story  being  now  re.idy  for  oc- 
cupancy, and  the  up[)er,  or  exhibition  room,  recjuiriiig  but  the  finishing 
coat  of  plastering,  the  painting,  and  the  finishing  of  the  tiling  of  the 


If 

(k>or?.     Tlie  hot  water  furnaces  are  completed  and  ready  to  be  put 
into  operation. 

Tlio  eastern  portico  is  nearly  finished,  and  the  steps  and  cheek 
Mocks  are  all  wrought  and  ready  to  be  set;  it  will,  therefore,  recjuire 
but  a  lew  weeks  to  complete  this  part  of  the  building  also. 

The  work  was  resumed  on  the  western  wing  in  the  monlli  of  Sep- 
tember, according  to  the  plans  which  were  laid  before  you  with  my 
last  annual  report,  and  the  granite  sub-basement  is  now  being  con- 
structed. 

THOMAS  U.  WALTER, 

Architect  of  Public  Buildings. 
Hon.  Alkx.  H.  H.  Stuakt, 
Stcrctanj  oj  the  Interior. 


Report  of  the  Commission  appointed  hj  the  Department  of  the  Literior  ^^to 
test  the  sevfral  specimens  (f  marble  offered  for  the  extension  of  the  United 
States  Capitol.''''     November  3,  1851. 

Washington,  D.  C,  December  22,  1851. 

Sir:  The  commission  to  which  has  been  referred  the  examination  of 
the  marbles  oflered  for  the  extension  of  the  Capitol,  have  been  informed 
that  vou  are  tlesirous  of  obtaining,  as  soon  as  j)ossible,  such  information 
as  will  enable  the  government  to  determine  which  of  the  several  marbles 
to  adopt.  Though  the  questions  proposed  to  the  commission  appear  to 
])e  simple  and  easy  of  solution,  yet  they  have  been  attended  with  many 
difficulties;  and,  notwithstanding  the  commission  have  pressed  on  the 
experiments  as  rapidly  as  the  nature  of  the  investigations  would  per- 
mit, and  have  devoted  more  time  to  the  subject  than  they  could  well 
spare  from  their  official  duties,  they  are  not  yet  able  to  present  as  many 
definite  results  as  they  could  desire. 

In  view,  howrver,  of  the  [)ressing  demands  for  lnf()rmation,  they  have 
concluded  to  make  the  fJjUowing  re[Mjrt  of  progress,  which  will  be  suf- 
ficient for  the  innnediatc  action  of  government;  and  they  would  respect- 
fully ask  for  permission  to  continue  their  investigations,  and  to  embrace 
in  thrrn  a  greater  varifty  of  the  building  mnterials  of  tliis  country. 

Though  the  art  of  building  has  been  practised  from  the  earliest  times, 
and  constant  demanrls  have  been  nifide,  in  every  age,  for  the  means  of 
determining  the  best  materials,  yet  the  process  of  ascertaining  the 
strength  and  durability  of  stone  appears  to  have  received  but  little  defi- 
nite scientific  atteiuion,  anrl  the  commission,  who  have  never  before 
made  this  subject  a  special  object  of  study,  liave  been  surpris(.'d  with 
unforeseen  difficulties  at  every  step  of  their  progress,  and  have  cr)me  to 
the  conclusion  that  the  processes  usually  employed  for  solving  these 
questions  are  still  in  a  veiy  unsatisfactory  state. 

It  should  be  recollected  that  the  stone  in  the  building  is  to  be  exposed 
for  centuries,  and  that  the  conclusions  desired  are  to  be  drawn  from 
results  produced  in  the  course  of  a  few  weeks. 

Besides  this,  in  the  present  state  of  science,  we  do  not  know  all  the 


11 

actions  to  which  the  materials  are  subjected  in  nature,  nor  can  we  fully 
estimate  the  amount  of  those  which  are  known. 

The  solvent  power  of  water,  which  even  attacks  glass,  must  in  time 
produce  an  appreciable  effect  on  the  most  solid  material,  particularly 
where  it  contains,  as  the  water  of  the  atmosphere  always  does,  car- 
bonic acid  in  solution.  The  attrition  of  siliceous  dusts,  when  blown 
against  a  building,  or  washed  down  its  sides  by  rain,  is  evidently  ope- 
rative in  wearing  away  the  surface,  though  the  evanescent  portion  re- 
moved at  each  time  may  not  be  indicated  by  the  nicest  balance.  An 
examination  of  the  basin  which  formerly  received  the  water'  from  the 
fountain  at  the  western  entrance  of  the  capitol,  now  deposited  in  the 
Patent  Office,  will  convince  any  one  of  the  great  amount  of  action  pro- 
duced principally  by  water  charged  with  carbonic  acid.  Again,  every 
flash  of  lightning  not  onlv  generates  nitric  acid — which,  in  solution  in 
the  rain,  acts  on  the  marble — but  also  by  its  inductive  effects  at  a  dis- 
tance produces  chemical  changes  along  the  moist  wall,  which  are  at  the 
present  time  beyond  our  means  of  estimating.  Also,  the  constant  vari- 
ations of  temperature  from  day  to  day,  and  even  from  hour  to  hour,  give 
rise  to  molecular  motions  which  must  aflect  the  durabihty  of  the  mate- 
rial of  a  building.  Recent  observations  on  the  pendulum  have  shown 
that  the  Bunker  Hill  monument  is  scarcely  for  a  moment  in  a  state  of 
rest,  but  is  constantly  warping  and  bending  under  the  influence  of  the 
var3-ing  temperature  of  its  ditterent  sides. 

INIoreover,  as  soon  as  the  pohshed  surface  of  a  building  is  made  rough 
from  an)''  of  the  causes  aforementioned,  the  seeds  of  minute  lichens  and 
mosses,  which  are  constantly  floating  in  the  atmosphere,  make  it  a  place 
of  repose,  and  from  the  growth  and  decay  of  the  nicroseopic  plants 
whicli  spring  from  these  discoloration  is  produced,  and  disintegration 
assisted. 

But  perhaps  the  greatest  source  of  the  wearing  away  in  a  diniMte 
like  ours,  is  that  of"  the  alternations  of  freezing  and  thawing  which  take 
pkice  during  the  winter  season;  and  though  this  elU'ct  must  be  com- 
parativ(;ly  j)o\verful,  y(;t,  in  good  marble,  it  requires  the  accumulated 
efl[ect  of  a  nunil)er  (jf  years  in  order  delinil(.'ly  to  estimate  its  amount. 
From  all  these  causes,  the  commission  are  convinced  that  the  only  en- 
tirely reliable  means  of  ascertaining  the  comparalive  capability  of  mar- 
ble to  resist  the  weather  is  to  study  the  actual  ( lli'c-ts  of  the  ainiosphere 
upon  it,  as  exhibited  in  buildings  which  f()r  years  ha\'e  been  exposed  to 
these  influences.  Unf()rtunately,  liowevcr,  in  this  couniiy,  bm  lew  oj)- 
portunilies  for  apj)lying  this  test  are  to  be  loimd.  Ii  is  line  sonic  ;iii;il- 
agous  itilormatioii  iiiav  be  derived  from  the  exainination  ol  the  e.\])ose(i 
surfiices  f)f"  marble  in  their  out-crops  at  the  (jiiarry  ;  liiit  in  this  case  the 
length  fit"  time  they  liave  been  exposiMl,  and  the  changes  of  actions  to 
which  tiiey  may  have  l)een  subjected  dining,  j)erhaps,  long  geological 
periods,  are  miknown;  and  since  diflircnt  (juarries  may  not  have  been 
exposed  to  the  same  action,  they  do  not  always  afli^rd  dclinite  d.ita  for 
reliable  comparative  estimates  of  durability,  except  wh<  r<^  dilierenl 
specimens  occur  in  the  same  (juarry. 

As  we  have  said  before,  tlic  art  of  testing  the  finality  of  stone  for 
buihlirii;  pnrposes  is  at  present  in  a  very  imperti'ct  slate;  the  object  is 
to  imitate  the  operations  of  nature,  and  at  the  same  time  to  hasten  the 


12 

effect  by  incrcnsiinG;  the  energy  of  the  action,  and,  after  all,  the  result 
may  be  doenied  but  as  approximative,  or,  to  a  considerable  degree, 
merely  ]iroiiable. 

Ai)()ul  twenty  years  ago  an  ingenious  process  \\as  devised  by  M. 
Brard,  which  consists  in  saturating  thestoiieto  be  tested  with  a  solution 
of  the  sulphate  of  soda.  In  drying  this  salt  crystallizes  and  expands, 
thus  )>r()dneing  an  exfoliation  of  surfice  which  is  supposed  to  imitate 
the  eHect  of  frost.  Though  this  process  has  been  much  relied  on,  and 
generally  employed,  recent  investigations  made  by  Dr.  Owen  lead  u& 
to  douT^t  its  perfect  analog}'^  with  that  of  the  operations  of  nature.  He 
found  that  the  results  produced  by  the  actual  exposure  to  freezing  and 
thawing  in  the  air,  during  a  ])orti()n  of  winter,  in  the  case  of  the  more 
porous  stones,  produced  vcr}'  diilerent  results  from  those  obtained  by 
the  drying  of  the  salt.  It  appears  from  his  experiments  that  the  action 
of  the  latter  is  chemical  as  well  as  mt^hanical. 

The  commission  in  consideration  of  this  have  attempted  to  produce 
results  on  the  stone  by  freezing  and  thawing  by  means  of  artilicial 
cold  and  heat.  This  process  is,  however,  laborious;  each  specimen 
must  be  enclosed  in  a  separate  box  fitted  with  a  cover,  and  the  amount 
of  exfoliation  produced  is  so  slight  that  in  good  marble  the  operation 
requires  to  l)c  repeated  many  times  before  reliable  comparative  results 
can  be  obtained.  In  prosecuting  this  part  of  the  inquiries  unforseen 
difficulties  have  occurred  in  ascertaining  precisely  the  amount  of  the 
disintegration,  and  it  has  been  found  that  the  results  are  liable  to  be 
vitiated  by  circumstances  which  were  not  foreseen  at  the  counnence- 
ment  of  the  inquires.  This  part  of  the  investigation,  ihcrelbre,  will 
require  a  long  series  of  experiments  in  order  to  obtain  results  entirely 
reliable. 

It  would  seem  at  first  sight,  and  the  commission  when  they  under- 
took the  investigation  were  of  the  same  opinion,  that  but  little  difficulty 
Would  be  found  in  ascertaining  the  strength  of  the  various  specimens 
of  marbles.  In  this,  however,  they  were  in  error.  The  first  difficulty 
wliich  occurred  was  to  procure  the  j)roper  instrument  for  the  purpose. 
On  examining  the  account  of  that  used  by  Rennie,  and  described  in 
the  Transactions  of  the  ]{o3'al  .Society  of  London,  the  commission 
fi>und  that  its  construction  involved  too  much  friction  to  allow  of"  definite 
comparative  results.  Friction  itself  has  to  be  overcome  as  well  as  the 
resistance  to  compression,  and,  since  it  increases  in  proportion  to  the 
pressure,  tlie  stronger  stones  would  appear  relatively  to  withstand  too 
great  a  comj)ressing  force. 

The  commission  first  examined  an  instrument — a  hydraulic  press — 
vrhich  had  jireviously  been  used  for  experiments  of  this  kind,  but  found 
that  it  was  liable  to  the  same  objection  as  that  of  the  machine  of 
Rennie.  They  were,  however,  extremely  fortunate  subsecjuently  in 
obtaining,  thrrjugh  the  p(jliteness  of"  Comniodore  Ijallard,  commandant 
of  the  navy-yard,  the  use  of  an  admirable  instrument  devised  by  Major 
"Wade,  late  of  the  United  States  arrny,  and  constructed  under  his  di- 
rectirm  for  the  purposf;  of  testing  the  strength  of  gun  metals.  This 
instrument  consists  of  a  compound  lever,  the  several  fulcra  of  which 
are  knife  edges,  opposed  to  hardened  steel  surfaces.  The  commission 
verified  the  delicacy  and  accuracy  of  the  indications  of  this  instrument 


13 

by  actual  weighing,  and  found,  in  accordance  with  the  description  of 
Major  Wade,  the  equihi^rium  was  produced  b}'  one  pound  in  opposition 
to  tico  hundred.  In  the  use  ol  this  instrumejit  the  commission  were 
much  indebted  to  the  experience  and  scientific  knowledge  of  Lieutenant 
Dahlgreen,  of  the  navy-3'ard,  and  to  the  Hberahty  with  which  all  the 
apphances  of  that  important  public  estabhshment  were  put  at  their 
disposal. 

Specimens  of  the  different  samples  of  marble  were  prepared  in  the 
form  of  cubes  of  one  inch  and  a  half  in  dimension,  and  consequently 
exhibiting  a  base  of  two  and  a  quarter  square  inches.     These  were 
dressed  by  ordinary  workmen  with  the  use  of  a  square,  and  the  oppo- 
site sides  made  as  nearly  parallel  as  possible  by  grinding  by  hand  on  a 
flat  surface.     They  were  then  placed  between  two  thick  steel  plates, 
and  in  order  to  insure  an  equahty  of  pressure,  independent  of  any 
want  of  perfect  parallelism  and  flatness  on  the  two  opposite  surfaces, 
a  thin  plate  of  lead  was  interposed  above  and  below  between  the  stone 
and  the  plates  of  steel.     This  was  in  accordance  with  a  plan  adopted 
by  Rennic,  and  that  which  appears  to  have  been  used  by  most,  if  not 
all,  of  the  subsequent  experimenters  in  researches  of  this  kind.     Some 
doubt,  however,  was  expressed  as  to  the  action  of  interposed  lead, 
which  induced  a  series  of  experiments  to  settle  this  question,  wlien  the 
remarkable  fact  was  discovered  that  the  yielding  and  aj)proximatcIy 
equable  pressure  of  the  lead  caused  the  stone  to  give  way  at  about 
halt  the  pressure  it  would  sustain  without  such  an  interposition.     For 
example,  one  of  the  cubes  precisely  similar  to  another,  which  witli- 
stood  a  pressure  of  upwards  of  60,000  pounds  when  placed  in  imme- 
diate contact  with  the  steel  plates,  gave  wa}^  at  about  30,000  with  lead 
interposed.     This  remarkable  fact  was  verified  in  a  series  of  experi- 
ments, embracing  samples  of  nearly  all  the  marl)lcs  under  trial,  and  in 
no  case  difl  a  single  exception  occur  to  vary  the  result.     Tlic  exj)lnna- 
tion  of  lliis  remarkable  phenomenon,  now  that  it  is  known,  is  not  dilii- 
cult.     Tlie  stone  tends  to  give  way  by  Ijulging  out  in  the  centre  of 
PAch  of  its  four  perpendicular  faces,  and  to  l()riri  two  pyramidal  figures 
with  their  apicf!S  opposed  to  each  other  at  the  centre  of  the  cube  and 
tlieir  bases  against  the  steel  plates. 

In  the  case  where  rigid  C(juabl(!  pressure  is  employed,  as  in  tliat  of 
the  thick  steel  plate,  all  parts  must  give  way  together.  I'.ut  in  iliat  of 
a  ycilding  equable  pressure,  as  in  the  case  of  interposed  lead,  the  stone 
first  gives  way  along  the  lines  of  least  resistance,  nnd  the  remaining 
pressure  must  be  sustained  by  the  central  portions  luound  the  vertical 
axis  of  the  cube. 

After  this  important  fnct  was  clearly  determined,  lend  and  all  oiher 
interposed  substances  were  discarded,  and  a  method  devised  by  which 
the  ut)per  and  lower  surfacr-s  of  the  cube  could  be  ground  info  j)er(i'Ct 
parelleli.-ni.  This  consist:*  in  the  use  of  a  rectangular  iron  frame,  into 
which  a  row  of  six  of  the  specimens  could  be  fastencfl  by  a  screw  at 
the  end.  The  upper  and  lower  snrfices  (»f  this  iron  frame  were 
wrought  into  perfect  parallc-lism  by  the  operalif)n  of  a  j)laning  machine. 
The  stones  being  fastened  into  this,  with  a  small  [xution  of  the  njjjxr  and 
lower  parts  projecting,  the  whole  were  ground  down  to  n  flat  surface, 
until  the  iron  and  the  face  of  the  cubes  were  thus  brought  into  a  conlinu- 


u 

ous  iihuu".  The  frame  was  then  turned  over,  and  the  opposite  surfaces 
frrouiid  in  hkc  manner.  Care  was  of  course  taken  that  the  surfaces 
llius  reduced  to  perfect  parallehsm,  in  order  to  receive  the  action  of  the 
machine,  were  jiarallcl  t(»  the  natural  beds  of  the  stone. 

All  the  specimens  testetl  were  subjected  to  Uiis  process,  and  in  their 
exposure  to  pressure  were  found  to  give  concordant  results.  The 
crushing  force  exhibited  in  the  sul)j()ined  table  is  much  greater  than 
that  heretofore  given  for  the  same  material. 

Tlic  commission  have  also  determined  the  specific  gravities  of  the 
dirterent  samples  submitted  to  their  examination,  and  also  the  quantity 
of  water  which  each  absorbs. 

The}'^  consider  these  determinations,  and  particularly  that  of  the  re- 
sistance to  crushing,  tests  of  much  importance,  as  indicating  the  cohe- 
sive force  of  the  particles  of  the  stone,  and  its  capacity  to  resist  most  of 
the  intluences  before  mentioned. 

The  amount  of  water  absorbed  may  be  regarded  as  a  measure  of  the 
antagonistic  force  to  cohesion,  which  tends,  in  the  expansion  of  freezing, 
to  disintegrate  the  surface.  In  considering,  however,  the  indication  of 
this  test,  care  must  be  taken  to  make  the  comparison  between  marbles 
of  nearly  the  same  texture,  because  a  coarsely  crystallized  stone  may 
apparently  absorb  a  small  quantity  of  water,  while  in  reality  the  cement 
which  unites  the  crystals  of  the  same  stone  may  absorb  a  much  larger 
quantitv.  That  this  may  be  so  was  clearly  estabhshed  in  the  experi- 
ments with  the  coarsely  crystalized  marbles  exaniined  by  the  commis- 
sion. When  these  were  submitted  to  a  liquid  which  slightly  tinged  the 
stone,  the  coloration  was  more  intense  around  the  margin  of  each  crys- 
tal, indicating  a  greater  amount  of  absorption  in  these  portions  of  the 
surface. 

The  following  table  exhibits  the  average  of  the  results  which  have 
been  obtained,  and,  although  they  do  not  give  the  data  for  estimating 
with  absolute  certainty  precise  relative  values,  yet  they  enable  the  com- 
mission to  pronounce,  with  consideraide  confidence,  that  the  first  four 
mur/jlf.i  (ire  of  a  superior  (jmilidj,  and,  it  is  believed,  will  2)rove  sufficiently 
durable  firr  the  work  proposed. 

Column  No.  1  gives  the  relative  resistance  to  crushing  per  square  inch, 
in  pf)unds  avoirdupois,  deduced  from  the  average  of  five  specimens  of 
each  s.imple. 

Cohnnn  No.  2  gives  the  specific  gravity  of  each  specimen  in  its  natu- 
ral condition,  without  allowing  for  thr  water  absorbed.  An  allowance 
on  this  account  would  slighlly  cluinge  the  numljers  presented. 

Column  No.  3  gives  the  wriglit  per  cubic  f()ot  in  {)f)nnds  avoirdupois. 

Column  No.  4  gives  the  (iu;intity  of  water  ab.«orl)ed  under  a  pressure 
of  about  fourteen  pounds  to  ihe  square  inch,  produced  by  placing  the 
stone  under  water  in  the  vacuum  of  an  air-pump,  and  afterwards  let- 
ting on  the  pressure  of  the  atmosphere. 

Column  No.  5  gives  the  relative  amount  of  material  thrown  off  in 
freezing  and  thawing  twenty-eight  times  in  succession. 

The  quantities  in  the  last  two  columns  are  expressed  in  weights  of 
which  the  unit  is  the  ten-thousandth  part  of  an  ounce.  These  of  the 
last  column  are  so  small  that  the  commission  would  prefer  to  repeat  the 
experiments  with  a  larger  number  of  specimens,  subjected  to  a  greater 


15 

number  of  alternations  of  freezing  and  thawing.  It  will  be  seen,  how- 
ever, that  the  results  coincide  in  a  considerable  degree  with  the  cohe- 
sive force,  as  exhibited  in  the  resistance  to  crusliing,  and  also  with  the 
specific  gravity. 

By  running  the  eye  down  the  column,  it  will  be  seen  that  the  several 
stones  may  be  divided  into  two  classes;  the  Hist  four  specimens  of  the 
table  exhibit  a  high  power  of  resistance  to  crushing,  and  a  high  spe- 
cific gravity.  In  the  remaining  eight  specimens,  there  is  a  sudden 
diminution  in  the  resistance  to  crushing,  and  also  in  the  specific  gravi 
ty.  The  same  change  exists,  though  in  a  less  marked  degree,  and  with 
some  exceptions,  in  the  last  column ;  and  when  we  take  into  consider- 
ation the  facts  which  we  have  stated  in  regard  to  absorption  by  a  fine- 
grained marble,  in  comparison  with  one  of  a  coarsely  cr3^stalline  struc- 
ture, the  results  in  the  fourth  column  are  also  not  discordant. 

It  must  be  understood  that  the  results  given  by  the  commission  re- 
late exclusively  to  the  particular  specimens  which  were  placed  in  their 
hands  as  the  samples  whicli  accompanied  the  bids.  From  these  spe- 
cimens the  cubes  experimented  on  were  cut  under  the  direction  of  the 
commission,  and  the  remainder  of  the  blocks  deposited  in  the  Smithso- 
nian l)uilding,  where  they  may  be  examined  by  those  who  are  inter- 
ested in  the  investigation. 

It  should,  moreover,  be  stated,  that  the  commission,  as  a  body,  have 
had  no  opportunity  of  examining  the  stones  in  masses  in  the  quarries, 
or  of  ascertaining  whether  they  could  bo  obtained  in  sufficient  quanti- 
ties, and  of  the  same  qualities  as  the  specimens  which  have  been 
tested.  Also,  whether  they  exhibit  the  presence  of  sulphuret  of  iron, 
or  other  contaminating  substances,  or  show  evidence  of  cracks  or  other 
unsoundness,  all  of  which  are  observations  of  importance  in  dctermLn- 
ing  the  above. 


IG 


The  following  is  a  table  of  the  mnrblcs  submitted  to  trial  by  the 
commission,  iirraiigcd  in  the  order  of  resistance  to  a  crushing  force: 


TABLE. 

Origmal  Nos.  of  samples. 

1. 

2. 

3. 

4. 

5. 

Localities  of  quarries. 

Ciiisliing  force  on  a 
square     inch,     in 
pounds     avoirdu- 
pois. 

Specific  gravity. 

Weight    per    cubic 
foot,     in     pounds 
avoirdupois. 

Absoqnion  of  water, 
in  ten-thousauths 
of  an  ounce. 

LoFS  by  freezing,  in 
ten-thousauths  of 
an  ouuce. 

East  Chester,  New  York 

1 

3 

9 

7 

4 

6 

2 

12 

11 

10 

5 

8 

23.  917 

22. 702 

IH.  941 

18.061 

10.  382 

9.  625 

9.544 

9.071 

8.950 

8.812 

8.  0.57 

7.  153 

2.  8579 
2.  8620 
2.8613 
2.  8605 
2.7143 
2. 7086 
2.7129 
2.7131 
2.7115 
2. 7129 
2.7128 
2.7089 

178. 62 
178.  87 
178.  83 
178.  78 
169. 64 
169. 29 
169.  56 
169.  57 
169.47 
169.  56 
169.  ,55 
169.  31 

39J 
103 
66 
52J 
68 
55 
92 
70,i 

«!•* 

87 

43J 

119§ 

6.2 
9.9 

11.8 

Baltimore,  small  crystal 

West  Stockbridge,  Mass 

Baltimore,  medium  crystal 

"^^■(•Tnniit    ^fnss      ......  ...... 

8.1 

8.8 

13.6 

15.7 

West  Stockbridge,  Mass 

Montgomery  county.  Pa 

Stockbriilgc,  Mass 

Baltimore,  large  crystal 

T jpnoT    Af iiss      ...  ............. 

(*) 
8.8 
25.7 
21.9 
24.1 

Respectfully  subnii 

•Ree 

ttod, 

ult  lost  by  a 

ccident. 

Hon.  Alex.  H.  H    Stuaut,  Secretary  of  the  Interior. 


JOS.  G.  TOTTEN. 
JOSEPH  HENRY. 
THOMAS  EWHANK. 
A.  J.  DOWNING. 
TllOiLVS  U.  WALTER. 


Report  of  rrrtfcxsor  TVtiltcr  R.  Johnson  on  the  hiildhig  stone  vsed  in  con- 
structing the  foundutions  of  the  extension  <f  tlic  United  States  Capitol, 
made  at  the  request  of  a  select  committee  of  the  House  of  RcpreseyUatives, 
consisting  (f  Hon.  John  McXair,  Hon.  J.  M.  H.  Beale,  Hon.  .Tames  H. 
Duncan,  Hon.  Daniel  JVallace,  and  Hon.  Thomas  A.  Hendricks. 

Washinctox,  D.  C.  March  11,  1852. 

Gextlemex:  In  confornjity  with  your  directions,  in.structing  me  to 
test  the  stone  used  in  the  Ibundation  walls  of  the  extension  of  the  Cap- 
itol, with  respect  to  their  strength  and  durability,  I  have  the  honor  to 
state  that  immediately  after  receiving  your  directions  I  proceeded  to 
inspect  the  walls  of  the  two  wings,  and  to  note,  as  lar  as  practicable, 
the  general  character,  and  the  apparent  differences  in  the  stones  which 
have  actually  been  laid  in  the  walls. 

I  had  no  difficulty  in  ascertaining  that  some  diversity,  both  in  ap- 
pearance and  texture,  existed  among  the  materials,  and  it  consequently 
became  evident  that  no  one  sample  wtiich  could  be  selected  would  ad- 
equately represent  the  entire  mass 


17 

It  therefore  became  necessary  to  select  a  moderate  number  of  sam- 
pics,  from  different  parts  of  the  two  wings,  and,  as  far  as  practicable, 
with  reference  to  the  proportions  in  which  they  seemed  to  prevail  in 
the  walls. 

It  is  evident  that  this  proportionality  could  only  be  approximately 
obtained. 

It  is  confidently  believed  that  the  extremes  of  character  have  been 
reached,  but  I  should  remark  that  the  sample  which  was  taken  to  show 
the  least  probable  strength  was  one  of  a  very  few  wliich  appear  mostly 
in  the  foundation  of  the  south  wing. 

Three  samples  were  taken  from  the  walls  of  each  wing,  besides 
which  a  block  lying  within  the  north  wall  was  taken  to  furnish  a  series 
of  cubes  of  different  sizes  to  test  the  question  of  increase  of  resistance, 
according  to  enlargement  of  area,  and  one  sample  of  the  sandstone  used 
in  two  or  three  of  the  interior  projections  onl}^  of  the  walls  of  the  south 
wing.  This  sandstone  is  of  the  same  character  as  that  of  which  the 
Capitol  is  built. 

The  samples  w^ere  prepared  for  trial  by  sawing  out  from  each  six 
cubes  of  one  and  a  half  inch  on  a  side,  which  were  all  carefully  dressed 
by  rubbing  down  in  the  ordinary  manner,  and  the  faces  which  were  to 
receive  the  compressing  force  were  made  parallel,  and  all  the  speci- 
mens of  very  nearly  the  same  height,  by  finishing  within  a  steel  frame, 
which  enclosed  and  held  all  the  six  specimens  at  the  same  time,  and 
which  being  turned  over  after  dressing  one  set  offices,  allowc^d  tlie  op- 
posite set  to  be  rubbed  in  like  manner,  and  made  parallel  to  the  first. 

This  frame  is  understood  to  be  the  same  which  was  employed  by 
Messrs.  Totten,  Henry,  Ewbank,  and  Walter  in  their  rcxHMit  trials  of 
the  marbl(!S.*  Of  the  six  cubes  from  each  sample,  one  was  selected 
and  reserved  for  trials  of  atmospheric  effects,  and  the  others  careliilly 
guaged  to  the  thousandth  part  of  an  incli,  pre[)aratory  to  the  opi'ration 
of  crushing.  In  general  the  specific  gravity  of  every  specimen  was 
taken  in  the  ordinary  way  before  crushing. 

For  the  sandstone  it  was  found  necessary  to  take  account  of  the 
water  absorbed  when  immersed  for  the  pinpose  of  taking  its  specific 
gravity. 

The  machine  used  for  crushing  is  that  employed  fi)r  the  ordnance  ser- 
vice of  the  navy  in  testing  the  various  materials  rc(|uire<l  for  that  service. 

It  consists  essentially  (j|"a.  lever  of  the  first  kind,  having  liilcrum  dis- 
tances of  20  to  1,  acting  by  its  shorter  arm  on  a  lever  of  the  second 
order,  having  fulcrum  distances  (»f"  10  to  I,  and,  eonsrcincnily,  ilie  i(  la- 
tion  (»f  the  weight  aj)plied  to  the  first  lever  to  the  lluce  (exerted  by  the 
second  is  1  to  20^). 

The  fulcra  of  the  machine  are  all  steel  knife  e(lgeif,and  no  allowance 
is  made  for  friction. 

The  compression  of  the  specimens,  win  n  under  trial,  was  ascertained 
frfim  time;  to  lime  by  suitable  crdipers  applied  by  steel  plates  above 
and   below  the  stone,  and  the  modulus  ol  rcsistcnce  to  compression 

'Tilts  mfftifid  of  <)t)fairiinR  a  jicrfrcf  juirnllfliMin  of  tho  l)|rirkR  whk  dcviHi'iI  by  tlic  fonimiB- 
nion  ti>r  tcsrini,'  the  iiiiirltlcH;  (in<i  tin-  [ilnii*  nii>i|il<Ml  liy  (licin  wrrc  follnwrii  tliniiiirluiiit  l>y 
Pn»fc8»or  .ffihnwm  in  (■••iidiirting  thedc  I'xjiiTiujt'iitd,  oh  will  be  seen  by  tbcir  rt'imrt  whirh  ina- 
mwliaU'ly  precedes  tbin  document.  -l  •  U.  \V. 


18 

\v;is  tlius  npccrtnincd  Aviili  considcrnble  exactness.  Tliis  modulus 
vari(\>i  considerably  in  dilioicnt  san)j)I(\'^,  and  oven  in  different  cubes 
iVoni  the  sanii!  saui])le.  In  order  to  obtain  a  standard  of  comparison  ot 
ilie  different  specimens  of  the  stone  ojicrated  on,  I  tested  a  sample  of  a 
rock,  largely  used  in  this  country,  and  to  some  extent  by  government, 
l()r  building  rnd  other  purposes. 

This  was  the  Quiney  sienite,  -svhich,  as  will  be  observed  by  reference 
to  the  table,  sustained  a  very  high  pressure  before  crushing.  In  testing 
the  action  of  the  atmosphere  on  the  different  samples,  I  may  remark 
that,  for  the  particular  purpose  of  the  foundations  of  the  Capitol,  I  do 
not  consider  that  ihe  trials  of  the  eff(>et  of  frost  are  very  important,  as  it 
is  understood  tliat  these  Ibundations  will,  when  the  building  is  comple- 
ted, be  embanked  in  such  a  manner  that  frost  will  never  reach  them. 

For  other  uses  to  which  this  stone  may  be  applied  these  trials  may 
be  of  much  importance.  To  some  extent  an  exemption  from  water  pin-- 
colating  the  soil  will  also  apply  to  the  foundations,  since  the  water  iall- 
ing  upon  the  building  will  be  mostl}'  carried  away  by  pipes  and  drains, 
and  the  shielding  of  the  surface  by  pavements  or  flaggings  will  tend  to 
keep  dry  the  foundation  walls. 

I  have  selected  for  the  chemical  trials  such  of  the  samples  as  ap- 
peared to  represent  the  exactness  of  strength  to  resist  crushing,  and 
have  subjected  them  to  such  re-agents  as  are  likely  to  be  most  efficient 
in  nature  in  causing  disintegration  or  dissolution. 

The  two  samples  taken  for  chemical  analysis  were  those  numbered 
one  and  seven  of  the  accoinpanying  table,  and  for  a  mechanical  separa- 
tion of  certain  mineral  constituents  No  5,  of  the  same  table,  was  chosen, 
being  one  of  those  which  appeared  to  have  been  freed  from  the  action 
of  atmospheric  influences  prior  to  its  removal  from  the  quarries. 

For  some  of  the  other  samples,  likewise,  the  effect  of  heating  was 
noted  by  way  of  comparison.  Having  visited  the  quarries  from  wliieh 
tlje  stone  is  stated  to  have  been  derived,  1  am  enabled  to  state  that  the 
one  from  which  the  stone  for  the  south  wing  was  taken  is  known  as 
the  Smith  quarry,  and  those  from  which  that  of  the  north  wing  is  taken 
are  the  O'Neill  (|uarries.  One  of  the  O'Neill  quarries  is  immediately  ad- 
jiininc'  that  of  iSmith,  and  these  two  appear  hi  furnish  stone  of  essen- 
tially the  same  character. 

The  other  (juarries  of  O'Neill  are  a  few  hundred  feet  lower  down 
the  canal.     At  all  these  quarries  I  judge  that  stone  may  be  found,  rc- 
prcs(  nting  every  variety  embraced  in  the  scries  of  specimens  selected 
lijr  trial  from  the  foundati(jns  of  the  Capitol.     At  all  of  them  there  is  a 
covering  of  greater  or  less  depth,  from  one  or  two  to  ten  or  twelve  feet  of 
soil,  sand,  gravel,  and  clayey  matter,  with  some  roffed  pebbles,  all  of 
which  repose  in  beds,  more  or  less  regular,  upon  the  upper  edges  of 
the  micaceous  rock,  worked   in  the  quarrifs.     This  rock  lies  inclined 
southwestwardly,  in  angle  of  about  oO  degrees ;   and  the  natural  beds 
and  fissures  of  the  stone  afford  ]:)assage  to  the  surface  water  to  pene- 
trate to  a  considerable  distance  below  the  upper  edges.     This  penetra- 
tirm  has  caused,   in   some  parts,  a  discoloration,   accompanie-d  by  a 
greater  oi    less  alteratifjii  fif  the  consistency  of  the  rock,   the   natural 
bluish  or  greenish  color  being  changed  to  a  yellowish  brown,  or  drab 


19 

color ;  and  for  about  20  or  25  feet  from  the  top,  the  rock  has  been  so 
affected  by  these  surface  influences  as  to  be  unfit  for  use  in  building. 

Below  that  level,  varying,  however,  in  the  different  strata,  the  work- 
able stone  is  found.  In  some  of  the  softer  portions  it  appenrs  that  the 
decomposition  has  extended  further  down  than  in  adjoining  firmer  beds. 

In  breaking  the  blocks  the  depth  to  which  atmospheric  influences 
have  penetrated  is  in  general  sufficiently  indicated  by  the  color.  A 
careful  inspection  enables  the  quarryman  to  reject  those  parts  which 
have  been  materially  affected  by  the  influences  above  referred  to;  and 
the  large  heaps  of  rejected  matter  near  the  quarries,  evince  the.  neces- 
sity and  the  exercise  of  a  discrimination  in  the  selection  of  such  parts 
as  are  fit  for  building  purposes.  The  discoloration  of  the  stone  is 
sometimes  only  superhcial,  or  extends  to  the  depth  of  but  a  few  lines. 
The  upper  edges  of  the  rock  next  to  the  covering  of  sand,  gravel,  &c., 
aflbrd  little  more  than  a  mass  of  micaceous  sand,  with  barely  cohesion 
enough  to  bear  handlino;. 

The  rock  in  its  normal,  or  solid  state,  appears  to  occupy  an  interme- 
diate place  between  tnoe  mica  slate,  of  which  flag-stones  are  made, 
and  gneiss,  whicli  has  the  mineral  composition  of  granite.  This  rock 
has  quartz  and  mica  in  large  proportions  as  compared  with  feldspar.  It 
exhibits  many  nodules  of  quartz,  nearly  pure,  and  small  garnets,  toge- 
ther with  iron  p3'rlte3,  and  m:ignetic  oxide  of  iron. 

I  submit  a  table,  exhibiting, yi/-6Y,  the  numl)er  of  samples  tested;  sec- 
ond, the  part  of  the  foundation  walls  from  which  they  were  severally 
taken;  i/uV(/,  the  numbers  of  the  several  specimens  taken  from  each 
sample;  fourth,  the  external  characters  of  each  specimen;  fif(k,  the 
S[)eci!ic  gi-avity;  sixth,  the  weight  of  each  sam])le  per  cubic  f)ot,  (kv 
rived  from  the  average  specific  gravity;  .«c«c/i^/t,  the  height  of  each 
6pfc;-imen  crushed ;  c/^A//t,  the  observed  compression;  yt/'/i^/i,  the  force 
producing  the  observed  compression;  tenth,  the  n\\\x  of  the  bas^j  of 
each  sp  -cimfni  opt-rated  on;  eleventh,  the  modules  ot" resistance  V)  com- 
pression ytf  each  specimen;  twelfth,  the  avenige  modulus  for  each  sam- 
ple; thiribk^nth,  the  average  crushing  force  per  scjuare  inch,  in  pounls; 
fourteenth,  t)ie  absorption  of  water  for  c;ich  smnple;  and,  Jiftccnlh,  the 
OSS  oi' cu/ii  sample  by  the  cflc'ct  of  heat. 


20 


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22 

In  condiu'tinG;  llio  experiments  on  crusliing,  the  opporfiinity  was  cm- 
brju'oil  of  ascertaining  the  amount  of  compression  wliieh  the  stone 
received  under  certain  loads  to  which  it  was  subjected.  The  observa- 
tions have  a  practical  bearing  when  applied  to  materials  of  variable 
cliar.icter  entering  into  tlie  slime  structure. 

h  the  weakest  varieties  were  at  the  same  time  those  which  could 
bear  the  least  compression,  it  might  happen  that  the  blocks  of  stone 
having  little  strengtli  to  resist  crushing,  as  well  as  little  capacity  to  un- 
dergo compr(\ssion,  might  be  crushed  and  destroyed,  while  tlie  stronger 
kinds  would  be  yieldiiig  to' the  compressing  force  and  would  be  event- 
ually brought  to  bear  tlie  whole  load.  If,  on  the  contrary,  tlie  weaker 
varieties  were  capable  of  yielding  to  compression,  without  linall}'  giv- 
ing way  until  considerably  condensed  by  pressure,  they  would  still 
preserve  their  integrity,  though  so  much  compressed  as  to  allow  the 
stronger  stones  in  close  proximity  to  them  to  bear  more  of  the  superin- 
cumbent weight  than  belonged  to  the  area  of  their  bearing  surfaces. 
As  the  compressibility  of  stones  may  be  considered  to  arise,  in  part  at 
least,  from  their  porosity,  and  as  the  latter  property  measures,  to 
some  extent,  the  power  of  the  stones  to  absorb  fluids,  it  ought  to  fol- 
low, that  when  a  stone  has  become  porous,  by  a  partial  decomposition, 
it  should  be  both  more  compressible  by  a  given  force,  and  more  absorb- 
ent of  iiuids  than  it  was  in  its  natural  or  unaltered  condition.  The 
experiments  furnish  a  remarkable  confirmation  of  this  view.  The 
table  ])ro"ses  that  the  samples  which  had  been  altered  by  partial  decom- 
position (Xos.  G  and  7)  were  nmch  more  compressible  ;  that  is,  they 
gave  a  lower  modulus  of  resistance  by  compression  than  any  of  the  sam- 
ples which  were  in  the  ordinary  unchanged  state  of  the  blue  rock. 
The  same  altered  samples  were  likewise  more  absorbent  of  water  than 
those  which  were  unaltered.  The  following  short  table  shows  the 
modulus  of  resistance  and  absorption  of  water,  arranged  with  relcsrence 
to  increasing  resistance  to  compression,  and  to  the  admission  of  water. 


Number  of  sample. 


weathered  stone, 

do 

not  weathered  . . 

do 

do 

do 


Modulus  of  resistance  to 

Absorption  of  water  in 

compression. 

grams. 

1,400,000 

5.88 

1,480,600 

4.20 

2,205,800 

1.20 

3,2G.'i,400 

0.90 

4,.'3 18,800 

0.81 

5,570,500 

0.G5 

The  differences  of  compressibility  are  obviously  not  solely  due  to  at- 
mospheric action. 

It  will  be  remarked  that,  instead  of  the  usual  term  "modulus  of 
elasticity,"  I  have  used  the  expression  "modulus  of  resistance  to  com- 
pression," which  seems  to  be  more  appropriate  to  express  that  charac- 


23 

ter  or  property  of  building  materials,  which  is  practically  apphed  in 
ai'chitecture. 

Examinations  to  illustrate  the  effects  of  atmospheric  injluences  on  the  stone. 

In  testing  the  action  of  frost,  I  have  appealed  directly  to  the  process 
of  freezing  the  specimens  after  moistening  them  with  distilled  water. 

This  mode  of  experimenting  (not  now  apphed  for  the  first  time)  has 
the  advantage  over  other  processes  sometimes  resorted  to  for  imitating 
the  effect  of  freezing,  in  producing  both  the  chemical  and  the  meclian- 
ical  actions  on  the  stone  which  naturally  result  from  atmospheric  hu- 
midity and  a  freezing  temperature. 

Each  cube  subjected  to  freezing  was  enclosed  in  a  thin  metallic  box, 
furnished  with  a  suitable  coverinG:,  and  the  whole  series  of  boxes  con- 
tammg  the  specimens  was  placed  within  a  larger  vessel  of  thin  metal, 
which  was  surrounded  by  a  freezing  mixture.  Care  was,  of  course, 
tiiken  that  all  the  particles  detached  from  each  cube  by  the  freezing 
should  remain  in  its  own  box.  The  gain  in  the  weight  f:f  the  box,  alter 
thirty  repetitions  of  the  freezing  process,  as  ascertained  by  a  balance 
sensible  to  the  two-hundredth  part  of  a  grain,  gave  the  loss  which  the 
stone  had  suffered  under  this  treatment.  Both  in  respect  to  the  absorp- 
tion of  water  and  to  the  influence  of  frost,  it  will  be  observed  that  the 
strong  rocks,  such  as  sample  No.  1  of  the  blue  quarlzose  mica  slate,  and 
the  Quincy  sieriite,  (sample  No.  9,)  manifest  great  power  to  resist  the 
disintegrating  action  of  these  powerful  causes.  While  sample  No.  1 
lost  only  t5o  of  a  grain  by  frost.  No.  6  lost  tottj  No.  7  ^Vo  'J"(l  the 
Aquia  creek  sandstone,  No.  8,  lost  -1-,^;,  or  exactly  12  times  as  nnich 
as  No.  1.  While  the  sample  No.  5,  a  very  sound  and  comj)act  v.nicly 
of  the  blue  rock,  absorbed  but  ^V  of  a  grain  of  water.  No.  G  took  l.xJU, 
No.  7,  5.88,  and  the  Aquia  creek  sandstone  199  grains. 

The  latter  acted  in  fact  like  a  sponge  and  became  completely  wet 
UnouLdiout. 

This  was  proved  by  crushing  some  cubes  of  that  stone  immediately 
after  they  li.ul  been  immersed  in  water.  It  is  pnjper  to  state  that  the 
absorption  of  water  is  represented  by  tht;  dilli'rencc  in  weight,  asccr- 
Uiiried  by  first  weighing  the  specimens  afUT  being  thoroughly  dried, 
and  ag;iin  aflir  being  permitted  to  absorb  water  by  the  aid  of  the 
exhausiion  of  an  air  jjump,  and  the  sub.-cijuent  j)icssure  of  the  atmos- 
phere while  immersed  in  a  vessel  of  water  within  the  receiver. 

Chemical  and  other  cxaminatioris  to  ascertain  the  vffccts  of  the  atmosj)here. 

I  have  not  sought  to  determine  the  exact  relations  of  llie  insoluble 
ingredients  of  the  rock  to  each  other,  since  neiih*  r  in  ;i  |)ractit;al  nor 
theoretical  view  would  the  information  thus  obtained  be  of  much 
value. 

The  rock  is  comjjoundcd  of  a  vari(;ly  (»f  different  miiier.ds,  .uid 
may  be  termed  a  quartzcjse  mica  slate,  in  which  the  (juartzose  constit- 
uent varies  from  point  to  j)oiiii,  and  the  garnets  and  other  silicious 
minerals,  usually  occurring  in  such  rocks,  vary  in  (|uantiiy  i"  dllli  rent 
spechnens.     Feldspar  is  less  abundant,  at  least,  far  less  distinctly  char- 


24 

nctcrlzcd  ns   such,   in  most  of  the  spocimcns  than  mica  and  quartz ; 
hence  the  apphcahiHly  of  the  name  in  preference  to  tlie  term  ^«em. 

When  present  feUlspar  is  hable  to  be  decomposed  by  the  action  Oi 
water,  or  of  water  impregnated  with  carbonic  acid,  taking  up  a  part 
of  the  siUcia  and  the  potash,  and  leaving  water  in  their  place,  as  a 
constituent  in  the  state  of  hydrates  of  silicious  compounds,  and  ot 
metallic-  oxides.  Tlie  lime  of  the  feldspar  is,  at  the  same  time,  converted 
into  carbonate  of  lime  by  the  carbonic  acid  accompanying  the  air  and 
water,  Mhich  dec;ompose  the  ieldspar.  From  this  reaction  comes  the 
ditlerence  well  known  to  exist  between  feldspar  and  kaolin  or  procehiin 
earth,  the  latter  of  which  is  derived,  from  the  decomposition  of  the 
former.  As  the  rock  contains  sparsely  scattered  particles  of  sul- 
])huret  of  iron,  and  also  iron  in  other  states,  a  mechanical  analysis 
was  made  on  a  specimen  which  was  considered  to  represent  fairly 
the  general  character  of  the  rock,  in  order  to  ascertain  the  per-centage 
of  that  sulphuret.  One  of  the  specimens  of  sample  No.  5  of  the  table, 
which  had  been  crushed,  was  taken  for  this  analysis. 

A  quantity  of  it  in  powder  amounting  to  2747 iVo  grains,  was  care- 
fully examined  in  small  portions  at  a  time,  by  the  aid  of  a  strong  mag- 
net, which  separated  the  magnetic  oxide  of  iron.  The  powder  was 
then  washed,  and  when  reduced  to  a  small  quantity  by  floating  off"  the 
lighter  particles,  the  sulphuret  of  iron  was  easily  separated  from 
among  the  black  sand  and  minute  garnets  which  remained  with  it. 
The  garnets  had  been  in  part  collected  while  pulverizing  the  stone, 
and  with  the  smaller  particles  gathered  as  above  amounted  to 

20  iVb  grains 0.744  p.  c. 

42  grains  magnetic  oxide  of  iron 1.528    "  " 

16  grains  iron  pyrites 0.058    "  " 

11.8  grains  black  silicious  sand 0.429    "  " 

Light  black  powder,  which  floated  on  immersing  the  pul- 
verized stone  in  water 0.001   "  " 

Sand  (silicious  and  micaceous)  with  dark  colored  clayey 

matter 97.240    "  " 


100.000 
The  very  trivial  quantity  of  sulphuret  of  iron,  found  by  this  analysis, 
confirms  the  impression  conveyed  by  the  inspection  reported  in  column 
4  of"  the  accompanying  table,  that  the  proportion  of  pyrites  (about  yy 
part  of  one  j)er  cent.)  is  too  insignificant  to  exercise  any  serious  influ- 
ence on  tlie  durability  of  the  stone,  especially  as  the  sulphuret  is  not 
collected  together  into  veins  or  pockets,  but  is  sparsely  scattered 
throughout  the  stone.  The  manganese  found  is  probably  in  the  state 
of  either  protoxide  or  protochloride  in  the  stone. 

Experiments  to  show  the  relative  condhum  of  the  altered  and  unal- 
tered samples  of  the  rock  in  respect  to  water,  cliemically  comljined, 
Sample  number  3  was  tried  by  placing  111  grains  in  fine  powder  in  a 
test  tube,  and  heating  a  little  above  the  boiling  point  of  water,  by  which 
0.26  per  cent,  of  moisture  was  expelled.  By  further  heating,  water 
continued  to  be  expelled  until  a  red  heat  was  attained,  when  the  quan- 
tity had  very  much  exceeded  that  driven  off  by  heating  to  the  boiling 
point.     Owing  to  accident  the  precise  quantity  was  not  ascertained. 


25 

Sam-pie  No.  1.  Fifty  gi-ains  of  this  sample  exposed  for  two  hours  to 
a  temperature  of  212^  lost  of  moisture  0.55  grain,  equivalent  to  1.1  per 
cent. 

17.75  grains  of  the  same,  heated  to  redness  for  an  liour,  lost  0.35 
grain,  equal  to  1.97  per  cent.  Hence  the  per  centage  of  water,  other 
thaji  adhering  moisture,  was  0.S7  per  cent. 

Sample  No.  2. — S4.55  grains  lost  of  moisture  only  0.1  grain,  or  0.118 
per  cent.  After  a  prolonged  exposure  to  a  red  heat  it  had  lost  0.75  of 
a  grain  more,  equal  to  0.SS7  per  cent.  From  this  it  should  seem  that 
the  rock  in  its  unaltered  condition  contains  0.875  per  cent,  of  water  in 
chemical  combination. 

Sample  No.  6. — Of  this  sample  89. 5  grains,  after  thorough  drying, 
had  lost  0.15  grains  =  0.1G7  percent.;  and  when  subsequently  heated 
to  redness  for  half  an  hour  it  lost  in  addition  1.3  grains  =  1.463  per 
cent. 

Sample  No.  7. — Of  this,  which,  like  the  preceeding,  was  a  weathered 
or  altered  rock,  50  grains  lost  in  drying  0.1  grain,  or  0.2  per  cent.,  and 
another  portion  of  the  same  powder  of  40  grains  lost,  by  a  continued 
ignition,  0.65  grain,  or  1.625  per  cent.,  from  which,  deducting  moisture, 
0.200  per  cent.,  there  remains  in  combination  1.425.  Tlie  mean  of  the 
two  trials  on  the  altered  stone  is  1.444,  from  wliich,  deducting  the  above 
mean  for  samples  1  and  2,  =  0.878,  we  have  the  excess  of  water  in 
the  hydrates  of  the  weathered  stones  =  0.566  per  cent. 

As  might  be  reasonably  anticipated,  this  replacement  of  a  portion  of 
the  mineral  ing?-edients  of  the  stone  by  water  is  acconip.-inicd  by  a  di- 
minution of  specific  gravity.  Thus  liom  column  six  ol"  ihc  ibrcgoing 
table  it  appears  that  the  avernge  weight  per  cubic  l()ot  of  Nos.  1,  2,  3, 
4,  and  5  (unaltered  stones)  is  174.15  pounds,  and  tlie  nn:in  weight  of 
Nos.  6  and  7  is  but  162.92  pounds.  Even  of  this  lalter  weight  it  ap- 
pears that  0.566  per  ccril.,  or  0.97  j)ouii(ls,  is  combined  water  added  in 
the  course  r;f  tlie  alteration.  This  being  (hnhietcd,  k-aves  of  the;  origi- 
nal mineral  constituents  only  171.95  pounds,  showing  that  2fo  pounds 
of  mineral  per  cubic  foot  have  been  extracted. 

Degree  of  solubiliti/  of  the  sfn/trs  in  arids. — 'I'he  ])ro(hicls  oi  llie  soil, 
such  as  the  vcgetabli;  acids  derived  liom  the  d('coMi|)o>ilioi)  of  plants, 
have  nr)  doubt  ro-operatcd  nioic  or  less  powerfully  with  the  atmosphere 
in  i)nKlucing  the  alterations  visiblr  at  tin;  (juarrifs  at  the  uj)pcr  part  of 
the  strata,  and  pcrcejjiibli;  on  the  cxti.'rior  or  interior  of  some  sam|)]es 
at  the  Capitol.  'J'hc  pow(,-r  of  tlu"  stone,  when  laid  in  buildinir,  to  n;- 
sist  the  further  ucUou  of  acids,  may  be  less  imporlani,  in  n-fficnce  to 
the  organic  products  of  the  soil,  than  win  u  exposed  in  llio  (junrriea  to 
their  influence  beiieaili  llic  natural  surface;  Imi  oiln  r  acids,  and  ihcir 
compounds,  may  and  do  |)ro{luce  on  the  materials  ol  buildinu's  ctlf els 
which,  in  the  course  of  time,  becouK!  suiruiently  marked.  Had  tune 
permitted,  it  would  jjave  been  desirable-  to  trace  distinctly  the  inllu- 
encc  of  the  several  causes  just  alludr-d  to,  and  note  the  jtrccise  effects. 
But  the  trials  would  be  long,  minute,  and  labr)rious. 

The  followini,'  trials  have  reference  to  tin;  total  amount  ol  matt(!i 
which  acids,  even  in  their  concentrated  f(»rm,  are  capable  ol  dissolving. 
Tliirty  grains  in  powder  of  sample  iNo  1,  .after  thf)roui;li  drying,  (where- 
by it  lost  0.1  of  a  grain,)  were  treated  with  strong  chhjrhydric  witii  a 


26 

little  nitric  acid,  and  the  treatment  repeated  with  fresli  portions  of  acid, 
until  everything  soluble  appeared  to  be  removed.  The  ignited  residue 
was  observed  to  contain  a  few  black  particles,  which  were  found  to 
be  magnetic  oxide  of  iron  removabU'  ijy  the  magnet.  The  residue 
weighed  25. Go  grains,  or  S2.17  per  cent,  of  the  original  assay.  Show- 
ing that  of  moisture,  combined  water,  and  mineral  water,  there  had 
been  removed  17.83  per  cent. 

On  sample  No.  7  (altered  rock)  30  grains  lost  of  moisture  O.OG  grain, 
and  these,  by  long  boiling  in  chlorhydric  with  nitric  acid,  wasliing, 
separating,  drying,  and  igniting,  left  a  residue  of  2G.23  grains,  of  which 
0.03  grain  was  magnetic  oxide  of  iron.  The  insoluble  part  is,  conse- 
quently, 87.43  per  cent,  of  the  original  weight,  and  the  part  dissolved 
is  12.57  per  cent.,  showing  a  marked  diflerence  between  this  partly 
decomposed  sample  and  the  unaltered  stone  No.  1.  The  insoluble  sili- 
cates are,  of  course,  left  in  the  rock  altered  by  natural  causes,  and  be- 
come a  larger  portion  of  the  whole  weight  than  in  the  unaltered  state. 
Of  the  matter  in  sample   1,  it  appears  there  were  of  insoluble   percent. 

silicates,  with  a  little  mametic  oxide  of  iron 82.17 

Hygrometric  moisture 0.33 

Combined  water 0.87 

Insoluble  matter  (silica)  left  in  drying  the  solution 0.60 

Peroxide  of  iron 6.30 

Lime 0.34 

^lagnesia 0.20 

Alumina 3.04 

Protoxide  of  manganese 5.09 

Potash 70 


99.64 
The  above  is  the  result  of  but  a  single  analysis,  which  I  should  de- 
sire to  repeat  and  vary,  did  time  permit,  in  order  to  assure  myself  of 
the  entire  accuracy  of  the  results. 

In  order  to  arrive  at  some  estimate  of  the  adecjuacy  of  the  founda- 
tion walls  to  support  the  structure  which  it  is  intended  to  place  upon 
them,  I  have  taken  from  the  working  drawings  of  the  architect  the  di- 
mensions of  the  main  walls  already  laid.  These  walls  are,  in  general, 
six  feet  nine  inches  thick,  but  at  those  parts  where  the  walls  are  high- 
est, the  base  resting  directly  on  the  ground,  it  is  widened  to  nine  feet. 
I  find  that  the  entire  circuit  of  each  wall  (not  including  the  porticoes) 
will  be  equal  to  a  single  wall  728  feet  long.  This  wall  is  to  support  a 
superstructure  34  feet  high  and  4J  feet  thick,  composed,  in  part,  of 
marble  weiuhing  about  179  pounds  per  cubit  foot,  and  in  part  of  other 
materials,  brick,  mortar,  &c.,  which  will  probably  weigh  considerably 
less;  but  I  have  assumed,  for  the  sake  of  giving  their  full  weight,  that 
the  entire  wall  will  weigh  175  pounds  [)cr  cubit  foot.  Conse(|uenlly, 
one  lineal  foot  of  superstructure  will  weigh  20,775  pounds.  This 
weight,  when  transmitted  to  the  base  of  the  foundation  walls,  where 
they  are  6f  feet  thick,  will  load  each  square  foot  with  a  weight  of  3,966 
pounds;  but  where  the  foundation  walls  are  9  feet  thick,  the  load  at  the 
base  due  to  superstructure  will  be  but  2,975  pounds  per  square  foot. 
The  highest  part  of  the  foundation  walls  themselves  is  stated  by  Mr. 


27 

"Walter  to  be  40  feet,  and  by  the  accompanying  table  it  appears  that 
the  stone  weighs  173  pounds  per  cubic  foot,  from  wliich  it  follows,  that 
a  vertical  wall  (not  widened  at  the  base)  would  press  that  base  with  a 
force  of  6,920  pounds  per  square  foot,  which,  iiddcd  to  the  pressure  of 
3,966  pounds,  due  to  the  superstructure,  would  give  a  total  of  10,SS6 
pounds,  which  would  have  been  the  load  at  the  bottom  of  the  founda- 
tion wall  at  its  deepest  part,  if  it  had  not  been  made  thicker  thnn  the 
rest.  If  this  deepest  part  of  the  foundation  be  gradually  thickened 
from  6f  feet  at  the  top  to  9  feet  at  bottom,  the  weight  of  it  distributed 
over  the  base  will  be  equivalent  to  a  load  of  6,05-5  pounds  per  square 
foot,  to  which  adding  the  weight  of  the  superstructure,  as  above  com- 
puted, for  the  same  9  feet  base,  viz:  2,97-5  pounds,  we  obtain  9,030 
pounds  on  one  scjuare  foot. 

By  a  reference  to  the  table  of  results  of  experiments  on  crusliing,  it 
will  be  found  in  column  thirteen  that  of  the  blue  micaceous  stones  No. 
7  gave  the  lowest  mean  strength,  viz:  8,156  pounds  per  square  inch. 
No.  1  gave  the  highest  result,  viz:  20,715  pounds;  and  the  average  of 
seven  samples  of  that  kind  of  stone  is  15,603  pounds  per  square  inch. 

8,156  lbs.  per  square  inch  is  at  the  rate  of  1,174,464  lbs.  per  sq.  foot. 
20,715  do  do  2,980,960  do 

15,603  do  do  2,246,832  do 

1,174,464  contains  10,886  one  hundred  and  eight  times. 

2,980,960  do  two  hundred  and  seventy-three  times. 

2,246,832  do  two  hundred  and  six  times. 

If  the  highest  part  of  the  foundation  had  been  built  only  6?  feet 
thick  at  bottom,  as  well  as  at  top,  and  wholly  of  the  w(Nd<fsi  kind  of 
stone  tested,  its  strength  would  have  been  5f  times  as  great  as  ihe  load 
to  be  supported  would  have  re(}uir(;d,  according  to  th(!  archili'cniral 
rule  in  relation  to  walls  of  rough  stone;  and  il'  made  9  lid  at  boiiom 
and  Of  at  toj),  having  to  bear,  as  above,  9,030  pounds  j)er  S(]uare  loot, 
the  crushing  fijrce  of"  tluj  stone  would  have  b(;en  6A  times  llic  r(>(piir(vl 
Strength.  11  constructed  of  stone  having  the  avtragr  sfn/ig/h  of  tlio 
seven  specimens  of  the  quartz  mica  slate,  the  wall  of  iV^  i\'c\  thick 
would  have  a  strength  ten  and  thrcc-tmtlix  times  as  great  ;i.s  tin;  above- 
mentioned  rule  would  r<(piire;  and  if  it  had  a  nine  feet  base,  as  be- 
fbrf!,  it  would  be-  twelv(j  and  two-fifths  times  as  strong  as  the  rc(|nire- 
ment  of  its  load. 

The  architectural  rule  to  which  I  have  just  r(;ferred  maybe  li»und  in 
Weisbacli's  "  Principles  of  the  Mechanics  (»f  Ma(  liineiy  and  Engineer- 
ing," American  edition,  vol.  1,  |)age  215.  in  a  slalenieiit  of  the  |)rae- 
tical  application  of"  the  ascertained  strength  of"  materials  to  resist  crush- 
ing, it  is  there  s;iid  that  "ten  times  iIk;  absolute  strength  is  given  to 
WfX)d  and  stones,  to  iron  only  one  of  live  times,  and  to  walls  of  rough 
stones  twenty  times.  Though  these  foundations  are  not  wholly  <>f 
rough  stones,  yet  as  they  are  so  in  ])art,  1  have  elK)sen  to  assume  that 
basis  of  computation  as  entirely  within  th(;  limits  of  safety,  whatever 
may  be  the  size  of  the;  specimens  composing  the  masonry. 

1  have  thus  far  spoken  of  the  force  pressing  on  the  bottom  of  thn 
founrlation  walls  at  their  dee[)est  part.  It  may,  j)erlia|)S,  be  said  that 
the  superstructure  does  not  rest  on  a  continuous  wall,  but  on  a  fbundu- 


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